Ratiometric fluorescence sensing NADH using AIE-dots transducers at the point of care.

Reduced nicotinamide adenine dinucleotide (NADH) has a strong impact on physiological metabolism, and its concentration is related to metabolic and neurodegenerative diseases. A more reliable and accurate detection method for NADH quantitation is needed for early disease diagnosis and point-of-care testing. Aggregation-induced emission (AIE) materials are widely used to improve the sensitivity in analytes assays due to their anti-aggregation-caused quenching property.

AND-Logic Cascade Rolling Circle Amplification for Optomagnetic Detection of Dual Target SARS-CoV-2 Sequences.

DNA logic operations are accurate and specific molecular strategies that are appreciated in target multiplexing and intelligent diagnostics. However, most of the reported DNA logic operation-based assays lack amplifiers prior to logic operation, resulting in detection limits at the subpicomolar to nanomolar level. Herein, a homogeneous and isothermal AND-logic cascade amplification strategy is demonstrated for optomagnetic biosensing of two different DNA inputs corresponding to a variant of concern sequence (containing spike L452R) and a highly conserved sequence from SARS-CoV-2.

Multienzymatic disintegration of DNA-scaffolded magnetic nanoparticle assembly for malarial mitochondrial DNA detection.

Early diagnosis of malaria can prevent the spread of disease and save lives, which, however, remains challenging in remote and less developed regions. Here we report a portable and low-cost optomagnetic biosensor for rapid amplification and detection of malarial mitochondrial DNA. Bioresponsive magnetic nanoparticle assemblies are constructed by using nucleic acid scaffolds containing endonucleolytic DNAzymes and their substrates, which can be activated by the presence of target DNA and self-disintegrated to release magnetic nanoparticles for optomagnetic quantification.

On-Particle Hyperbranched Rolling Circle Amplification-Scaffolded Magnetic Nanoactuator Assembly for Ferromagnetic Resonance Detection of MicroRNA.

Inspired by natural molecular machines, scientists are devoted to designing nanomachines that can navigate in aqueous solutions, sense their microenvironment, actuate, and respond. Among different strategies, magnetically driven nanoactuators can easily be operated remotely in liquids and thus are valuable in biosensing. Here we report a magnetic nanoactuator swarm with rotating-magnetic-field-controlled conformational changes for reaction acceleration and target quantification.

Apex-Confined Plasmonic Tip for High Resolution Tip-Enhanced Raman Spectroscopic Imaging of Carbon Nanotubes.

This paper reports a handy technical scheme to decorate atomic force microscopy (AFM) tips toward tip-enhanced Raman spectroscopy (TERS) applications. The major attraction of these homemade tips lies in that silver decoration can be confined at the apex of commercial tips by the means of an AFM-controlled electrochemical reaction. The reduction of Ag occurs in a highly sealed environment to secure the metal coating efficiency.

Calling the amino acid sequence of a protein/peptide from the nanospectrum produced by a sub-nanometer diameter pore.

The blockade current that develops when a protein translocates across a thin membrane through a sub-nanometer diameter pore informs with extreme sensitivity on the sequence of amino acids that constitute the protein. The current blockade signals measured during the translocation are called a nanospectrum of the protein. Whereas mass spectrometry (MS) is still the dominant technology for protein identification, it suffers limitations.

Measurements of the size and correlations between ions using an electrolytic point contact.

The size of an ion affects everything from the structure of water to life itself. In this report, to gauge their size, ions dissolved in water are forced electrically through a sub-nanometer-diameter pore spanning a thin membrane and the current is measured. The measurements reveal an ion-selective conductance that vanishes in pores <0.

Method for Dynamically Detecting Secretions from Single Cells Using a Nanopore.

Secreted proteins mediate cell-to-cell communications. Thus, eavesdropping on the secretome could reveal the cellular phenotype, but it is challenging to detect the proteins because they are secreted only in minute amounts and then diluted in blood plasma or contaminated by cell culture medium or the lysate. In this pilot study, it is demonstrated that secretions from single cancer cells can be detected and dynamically analyzed through measurements of blockades in the electrolytic current due to single molecules translocating through a nanopore in a thin inorganic membrane.

Discriminating Residue Substitutions in a Single Protein Molecule Using a Sub-nanopore.

It is now possible to create, in a thin inorganic membrane, a single, sub-nanometer-diameter pore (i.e., a sub-nanopore) about the size of an amino acid residue.

Single-molecule protein identification by sub-nanopore sensors.

Recent advances in top-down mass spectrometry enabled identification of intact proteins, but this technology still faces challenges. For example, top-down mass spectrometry suffers from a lack of sensitivity since the ion counts for a single fragmentation event are often low. In contrast, nanopore technology is exquisitely sensitive to single intact molecules, but it has only been successfully applied to DNA sequencing, so far.

Reading the primary structure of a protein with 0.07 nm resolution using a subnanometre-diameter pore.

The primary structure of a protein consists of a sequence of amino acids and is a key factor in determining how a protein folds and functions. However, conventional methods for sequencing proteins, such as mass spectrometry and Edman degradation, suffer from short reads and lack sensitivity, so alternative approaches are sought. Here, we show that a subnanometre-diameter pore, sputtered through a thin silicon nitride membrane, can be used to detect the primary structure of a denatured protein molecule.

Determination of mechanical properties of soft tissue scaffolds by atomic force microscopy nanoindentation.

While the determination of mechanical properties of a hard scaffold is relatively straightforward, the mechanical testing of a soft tissue scaffold poses significant challenges due in part to its fragility. Here, we report a new approach for characterizing the stiffness and elastic modulus of a soft scaffold through atomic force microscopy (AFM) nanoindentation. Using collagen-chitosan hydrogel scaffolds as model soft tissue scaffolds, we demonstrated the feasibility of using AFM nanoindentation to determine a force curve of a soft tissue scaffold.